51�Թ�

A type of bed net called a PBO net that contains pyrethroid and piperonyl butoxide, a compound that enhances pyrethroid’s effectiveness, would be substantially more effective than pyrethroid-only nets5.

The new nets contain pyrethroids, a class of chemicals used in nets for over a decade, along with the newer compound, piperonyl butoxide, which blocks mosquitoes’ ability to break down pyrethroids.

Piperonyl butoxide largely fades away after two years.

In the study’s second year, protection by nets with piperonyl butoxide had diminished, and malaria prevalence in children was reduced by only 33 percent.

But the pesticide also contains a substance — piperonyl butoxide — that is classified by the U.S.